The story in the Bible on Noah is a parable, but is based on an actual incident, or multiple incidents.
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I do not see anything in Scripture that would indicate it is a parable, it is a recording of history if you read Genesis, it records history.
One day, maybe, we will be able to prove it all happened exactly as stated in Genesis.
Yet, I suspect, we will continue to ignore the lesson.
No less than Jesus himself authenticated what happened, and the flood itself is not the important event here, it was for (and because of) what occurred in Genesis Chapter 6,
When the end of the age comes upon us, in our future, it begins out of a blue sky day, just like in the days of Lot and Noah and will be of fire and not water:
“But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only. But as the days of Noe were, so shall also the coming of the Son of man be. For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, And knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.” Matthew 24:36-39
“For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment; And spared not the old world, but saved Noah the eighth person, a preacher of righteousness, bringing in the flood upon the world of the ungodly; And turning the cities of Sodom and Gomorrha into ashes condemned them with an overthrow, making them an ensample unto those that after should live ungodly; . .”
2 Peter 2:4-6